Microbiological Safety of Space Equipment
Development of Means and Methods to Ensure Microbiological Safety of Long-Operating Space Equipment
Tech Area / Field
- SAT-SAF/Space Safety/Space, Aircraft and Surface Transportation
8 Project completed
Senior Project Manager
Russian Academy of Sciences / Institute of Biomedical Problems, Russia, Moscow
- FEI (IPPE), Russia, Kaluga reg., Obninsk
- SCK-CEN, Belgium, Mol\nBremen Institute for Materials Testing, Germany, Bremen\nUniversita degli studi della Tuscia / Dipartimento di Agrobiologia e Agrochimica, Italy, Viterbo\nUniversity of Groningen / University Medical Center Groningen, The Netherlands, Groningen\nUniversität Bremen / UFT, Germany, Bremen
Project summaryThe goal of our work is searching for means and development of methods to provide prolonged protection of construction materials and equipment used on space vehicles from microbial colonization, biodegradation and biocorrosion as well as improvement of means of maintenance of biological cleanness in the period of pre-launch activities.
Based on the Russian experience with long-operating spacecrafts, extension of the flight period piles up ecological problems of the closed environment affecting equally crew safety and equipment reliability. Among the others, the microbial factor is of the utmost criticality.
Spending much effort to create and maintain adequate living conditions aboard a space vehicle, the human yet inevitably sets the stage for vital functioning of microorganisms, proliferation of which cannot be unfailingly controlled by the crew with available technical means.
Processes of microbial contamination of the environment, equipment and belongings of the habitable compartments proceed with high intensity on a backdrop of continuous presence of rotating crews, cargo traffic (delivery from Earth of exchange parts, expendables etc.), and the use of systems regenerating human wastes. After many years of orbiting, space vehicles become the most favorable setting for microbiotas to demonstrate their power of selectivity and adaptability, as well as mutability, and for different groups of microorganisms to use space modules for residence, a kind of peculiar eco-niche. Obviously, these processes may assume a dangerous and irreversible character due to the presence of, specifically, human pathogens and microbes-biodestructors, which threaten, according to the experience of exploitation of orbital station MIR and International Space Station (ISS), with biodegradation of structural materials, failure and malfunctioning of equipment, and because of impracticability of the total sterilization procedures in space flight.
ISTC project 1346 allowed us a construction of a unique simulation stand (two – test and control - climatic chambers) reproducing the physical and physical/chemical parameters of the space modules environment (temperature, relative air humidity, air flows, light intensity, radiation and electromagnetic fields, precipitation of atmospheric condensate chemically identical to the one collected in the space cabins) and can cause significant impact on the type of interaction of microorganisms with construction materials. Hence, the prime objective of this project is to enhance the stand reproducing the spaceflight environment by integration of components that will enable simulation of off-nominal events (contingencies).
At present, microbiological cleanness on the phases of flight preparation and operation of space vehicles is maintained with the help of disinfectants (biocides). However, they are not free from some drawbacks like: time-bounded effect and, consequently, the need to periodically repeat disinfecting procedures, crew-intensity, impossibility to clean difficult-to-reach places.
A more radical and forward-looking solution could be microbial proofing of materials. Yet, straightforward integration of a biocide into the material structure as part of the production technology will not guarantee a long-term anti-microbial protection for the reasons of low superficial concentration of biocide, and also because low-molecular biocides leave high-molecular polymers too quickly (sweat-out).
Within the completed ISTC project 1346 we undertook R&D of methods of superficial materials modification to prevent microbial contamination and biodegradation. Tested were several methods (radiation-assisted inoculative polymerization, chemical surface modification) the essence of which is immobilization, by way of chemical bonds, of biocide-containing compounds or, in other words, chemical binding up of biocides with material surface. It was also possible to demonstrate high protective efficiency of the method as applied to fibrous materials with varying chemical composition.
However, the method was less successful when applied to smooth materials (polymer films, optic glass and others) and metals. In addition, the method was found unfit for anti-microbial protection of finished products (devices, equipment, interior components etc.). The best approach to the problem would be development of polymer film coatings with in-built chemically bound biocides.
The second objective is development of a methodical and technological basis for production of biocide film coatings with a broad anti-microbial spectrum and prolonged effect. The third objective can be achieved after fulfillment of the two previous tasks. It includes evaluation of effectiveness and selection of biocide film coatings that will impart the anti-microbial properties to space structural materials to prevent their biodegradation and biocorrosion.
By this day, there have been developed and approved a package of guidelines setting rules to ensure microbiological safety of the International space station (ISS) modules, transport vehicles and cargos, and describing associated practices. However, results of the microbiological monitoring of the ISS environment and data of analysis of the quality of disinfecting the ISS compartments and cargos point to the necessity for improvement of current methods and means used to provide biological cleanness on the pre-launch phases. There is a number of physical methods of decontamination of objects from microorganisms including pulsed ultraviolet, laser optic coherent radiation, pulse microwave radiation, ultrasonic treatment, power and hardness-controlled X-rays). The point is, that these methods have not been tested for applicability to the space industry.
We cannot overlook the problem of bioterrorism, to which much attention is paid at the present time in different countries.
Thus, improvement of means and methods of biological cleanness of modules, cargo vehicles and cargoes on the pre-launch stage is seen as the third task of the project. For this purpose evaluation of physical methods of air sterilization in the lodgements, where preparatory activities are held, is necessary as well as investigation into the possibility of application of various physical methods for desinfection of surfaces and articles. It is not only important to study and choose efficient methods but also to work out regimes of functioning of prototypic devices for this purpose. Logically, as a result, techniques for the application of physical methods for biological cleanness and desinfection of space vehicles and cargoes will be offered.
Achievement of the above objectives of the project will enhance safety of space flights owing to reliable operation of space equipment and maintaining optimum ecological environment for space crews.
Implementation of project 1346 has brought together an energetic team of immensely qualified scientists, engineers and technicians from SRC RF - IBMP RAS and SRC RF-Leipunsky PEI.
The proposed project serves to reorient former developers of nuclear weapons to the peaceful purposes, and integrate all participants into an international scientific association.